1. Field of the Invention
This invention relates to an image information reading apparatus which reads the original by utilizing the light that passes therethrough or is reflected thereby and which is used in the image scanner, printer, facsimile, etc.
2. Description of the Related Art
In the image information reading apparatus used in the image scanner, printer, facsimile, etc., an explosure light is projected onto the original placed on the original table and the transmitted light or the reflected light from the original is converted by the photoelectric transducer of the scanner into electric signals. In this way, desired image signals are input into the host computer. The scanner is driven by a well-known drive means to reciprocate over the original table. The control circuit built in the main body is used to control the above operation and the processing of signals.
Conventionally, the image information reading apparatuses are produced in two different types, one type for reading information from an original for reflected light and the other type for reading information from an original for transmitted light. Meanwhile, an image information reading apparatus has been developed which is capable of reading information both from originals for reflected light and transmitted light. In this type of apparatus, a scanner comprising a photoelectric transducer and a light source is installed in the main body fitted with a platen glass (original table). Provided outside the main body is a transmission unit, which has a light source section for projecting light onto an original for transmitted light mounted in a position opposed to the platen glass (U.S. application Ser. No. 50,012). The light source section of the transmission unit faces the scanner across the platen glass. When an original for transmitted light is read, the light source section of this transmission unit which is synchronized with the scanner is moved with the scanner at the same speed and in the same direction. Therefore, this reading apparatus requires a drive means to drive the scanner and another drive means to move the light source section in the transmission unit.
This reading apparatus is convenient indeed because it is capable of reading information both from originals for reflected light and transmitted light, but it carries with it a problem that the light source unit and the drive unit included in the transmission unit are lying idle when this reading apparatus is used only for reading original copies for reflected light.